Alveolar Oxygen Content
PAO2= FIO2 (Pb-47) - (PaCO2/0.8)
%Body Humidity
(Absolute Humidity/43.8) x100
%Relative Humidity
(AH/Saturated Capacity) x100
Oxygen Consumption
VO2= QT [C (a-v) O2] x 10
Oxygen Extraction Ratio
O2ER= CaO2-CvO2/ CaO2
Hb Saturation
SaO2= [Hbo2/Total Hb] x100
A-a Oxygen Tension Gradient
P (A-a) O2= PAO2-PaO2
Oxygen Content of Arterial Blood
CaO2= (Hbx 1.34x SaO2) + (PaO2 x 0.003)
Oxygen Content of Mixed Venous Blood
CvO2= (Hb x 1.34 x SvO2) + (PvO2 x 0.003)
Oxygen Content of Pulmonary Capillary Blood
CcO2= (Hb x 1.34X SaO2) + (PaO2 x 0.003)
Total Oxygen Delivery
DO2= QT (CaO2 x 10)
Pulmonary Shunt Fraction
Qs/Qt= CcO2-CaO2/CcO2- CvO2
Arterial- Venous Oxygen Content Difference
C(a-v) O2 = CaO2- CvO2
Farenheight to Celsius
F-32= 1.8 (C)
Kelvin
K= C+273
Boyle's Law
P1 x V1= P2 x V2
Charles' Law
V1/T1= V2/T2
Guy-Lussac's
P1/T1= P2/T2
Combined Gas Law
(P1x V1)/ T1= (P2 x V2)/ T2
Minute Ventilation
Vt (tidal volume) x RR (respiratory rate)
Ideal Body Weight
Male: 106 +6 (Height in inches -60)
Female: 105 +5 (Height in inches - 60)
Duration of Flow (min)
Duration of Flow (min)= Pressure (psig) x cylinder factor/ Flow (L/min)
Amount of Gas in Cylinder
Liquid O2= weight(lb) x 860/ 2.5 lb/L
Duration of Gas (min)
Amount of Gas in Cylinder(L)/ Flow (L/min)
%O2
(Air Flow x 21) + (O2 Flow x 100)/ Total Flow
Cylinder Factor (L/psig)
Cubic Feet (full cylinder) x 28.3/ Pressure(full cylinder) in psig
Shunt Equation w. or w/o CPAP
Qs/Qt= CcO2-CaO2/5+CcO2- CvO2
Shunt Equation w. or w/o PEEP
Qs/Qt= CcO2-CaO2/3.5+CcO2- CvO2
Shunt Equation : Modified
Qs/Qt= (PAO2- PaO2) x 0.003/(CaO2- CvO2)+ (PAO2-PaO2) x 0.003
Anion Gap
Agap =Na+ -(Cl- +HCO3-)
Arterial/Alveolar Oxygen Tension (a/A) Ratio
a/A = PaO2 /PAO2
Arterial-Mixed Venous Oxygen Content Difference
[C (a - v) O2]
amount of O2 dissolved in 100mL
PaO2 x 0.003